Watch: What you need to know about al Shabaab

Al Shabaab, the Somali terror group that stormed into a Kenyan mall killing dozens and taking others hostage this weekend, is an al Qaeda affiliate that has recruited American fighters.

“It’s not just a jihadi group. They’re waging a civil war inside Somalia. It’s not just a couple hundred guys, it’s several thousand guys, maybe more,” said Evan Kohlmann, an international terrorism consultant, on MSNBC Monday. “They control a vast swath even with the Kenyan army occupation. They have quite a bit of foreign fighters as well. I think that’s one of the elements that we’ve been most concerned about is the fact that foreign fighters who align themselves with al Qaeda, even people from here in the United States, have gone there to join them not just to fight in a liberation battle against the Kenyans but with the idea of practicing violent jihad and striking back at the United States.”